This invention relates to gas turbine fan engines and particularly to the exit guide vane of the turbine and the mixer for the core and fan gaseous flow.
It is well known in engine technology to include a mixer downstream of the turbine to mix the fan discharge air with the turbine discharge air to achieve noise suppression. Typically, the mixer is a lobed type that is, for example, described in U.S. Pat. No. 3,508,403 granted to R. E. Neitzel on Apr. 28, 1970 to which reference should be made for further details.
Typically, turbine gases exhaust with a high swirl velocity component and the guide vanes mounted just downstream of the turbine ahead of the mixer serve to straighten the flow. However, in straightening the exhaust gas an increase in pressure losses results adversely affecting the efficiency of the power plant. Moreover, the turning vanes with their attachment structure are complicated and heavy and require additional space.
Since the lobe mixer acquires some length in order to direct the primary and fan flow into the proper position for mixing, this invention contemplates the effective use of this length by combining the guide vanes with the mixer. This not only shortens the overall length of the engine with a consequential weight savings, it minimizes and even eliminates the pressure losses.